Embodiments of the invention generally relate to integrated circuits. More specifically, the embodiments of the invention relate to array capacitors that are used in integrated circuits.
In known integrated circuits, a capacitor, such as a discrete array capacitor, is used to decouple the noise present on a power rail. Typically, when discrete capacitors are used to decouple the noise on multiple power rails, one or more discrete capacitors are used for each power rail. The capacitors can store charge and supply current on a temporary basis until the current supply kicks in. In addition, in known integrated circuits a plurality of discrete capacitors is used to decouple multiple voltage rails.
As microprocessor speeds increase, there is a demand for high performance decoupling capacitors. One such capacitor is the array capacitor which has significantly larger number of terminals and has better performance than standard discrete capacitors. For example, in case of a semiconductor device, which may include a plurality of voltage rails such as an Input/Output (I/O) voltage rail, a core voltage rail, and a cache voltage rail, a plurality of array capacitors can be used to decouple the plurality of voltage rails. However, there are often design criteria that restrict how close the multiple array capacitors can be placed to each other, which can limit the amount of capacitance per unit area. Therefore, there is a need for a single array capacitor which can decouple multiple voltage rails.